Battery life of Petzl Tikka 2 Plus w/ CORE rechargeable pack?

The decreased capacity of LithiumIon is inherent to the technology and not the application of the technology.

http://en.wikipedia.org/wiki/Lithium-ion_battery

So, yes, like your MacBook it will see diminished capacity over time. It does not have the "memory" of the old NiCad/NiMH batteries though.

The implication that it's worth 300recharges x 185 hours (or whatever the real-world numbers end up being) is probably marketing. Whether that 300 recharges is pre- or post- inflection point on the point of diminishing returns is unknown.

You may end up with 300 full and N-diminished…or 250 full and M-diminished … or 340 full and L-diminished. Some of this is the LI tech and some of this is the actual manufacture of the battery itself.

Either way, I have the CORE, use it, love it, and you can recharge in the field by carrying a solar charger, whose weight is offset by "I can recharge my phone, lights, kindle, etc from a single micro-USB source instead of carrying any extra batteries at all." Purists and cloudy-days need not apply within. :) I do cheat and carry 1 set of lightweight AAA lithiums though, just in case. I can do without a lot of things, but not having a light is one where I'll (personally) splurge on the safe side.

-mox

I actually subverted my second question with that same Wikipedia article and a very helpful Yahoo answer.

For others, here's what I found out:

1. Degradation is caused by the build-up of deposits in the battery. Running a Lithium Ion battery at 40-60% charge decreases the overall rate of degradation over time by about half. instead of losing 20% capacity per year, you'll lose 10%.

2. The #1 way to burn through your capacity is to run the battery at high heat. So keep these suckers in the shade.

3. Recharging the battery a little bit as often as you can is better than recharging it a whole lot all at once.

I don't think I can realistically handle #1, I would want to leave the house with a 100% charge every time. I guess this one, I will just have to cope with.

To compare the life of a rechargeable battery to an alkaline you need to look at the mAhr ratting of the two batteries. The 900mAhr rating means the battery can supply 900mAhr of current for 1 hour. In comparison a Panasonic disposable Alkaline puts out 1125mAhr. So the disposable AAA batteries will store more power than the rechargeable battery. Exactly how that translates to hours of operation will depend on the design of the electronics of the head lamp. The AAA batteries when wired in series will supply 4.5V while the lithium is about 3V. I don't know how that 1.5V difference translates into lamp hours. The only way to know if the rechargeable lithium will last 185 hours is to actually test it.

As to your second guestion, All rechargeable batteries will wear out over time. How fast is determined by the construction of the battery, its chemistry, and the recharging circuit. Some batteries will last a long time. Others won't.

So overall the best way to determine the if the lamp will go 185 hr with the rechargeable battery is to actually test it. But as the battery ages the operating time of the lamp will drop. How much and how fast is impossible to determine with the information presented.

I like the Core battery which I use in an Tikka XP2. I feel the real benefits of the Core battery system are that:
– it provides a regulated power supply so you get constant light output
– it provides customisable high and low power levels so you can dial in what works for you and potentially extend run times considerably by setting lower power levels
– you only need to recharge around 6 times to start saving money over buying lithium primary cells (about $5 each in Australia) or 15 times for alkalines.

If I get 300 charges out of one I will consider it a great buy.

Right, but if I can only go a few days before I need to charge via USB, I will not be pleased. I guess I can carry backup batteries, which I would anyways.

Ok, for anyone looking for info, the CORE software tells me the hours I get on each charge:

With continuous, even light, I can get 24 hours on the full 90 lumens and 48 hours on economy mode.

With declining light, I can get 24 hours of the full 90 lumens and up to 90 hours in economy mode, but that's it.

So, AAA batteries last longer. At least I always carry them.

The CORE is also pretty beastly size-wise. I think SUL or very UL hikers would notice this substantial light, but it seems to be good quality and not wasteful. It's definitely heavier than my old Princeton Tec headlamp.